Resin-fortified emulsion polymers and methods of preparing the same

ABSTRACT

The stability and physical properties of high molecular weight emulsion polymers are improved by the addition of a low molecular weight support resin during the emulsion polymerization process. The resin is soluble or dispersible in water or alkali and has a number average molecular weight between 500 and 20,000.

This application is a continuation of U.S. Application Ser. No. 899,281 filed Aug. 22, 1986 in the name of Sheng-Liang Tsaur entitled "Resin-Fortified Emulsion Polymers and Method Of Preparing The Same."

BACKGROUND OF INVENTION

The present invention relates to resin-fortified emulsion polymer compositions having improved mechanical and physical properties. Additionally, the present invention relates to methods of preparing these resin-fortified emulsion polymers.

High molecular weight emulsion polymers are gaining wide acceptance in the coatings industry. However, high molecular weight emulsion polymer technology has many drawbacks. Problems associated with high molecular weight emulsion polymer systems include poor wetting of metal substrates, cratering of resulting films, low gloss or mudcaking of resulting films, wetting and adherency problems, mechanical instability, freeze-thaw instability, shear thinning and poor physical properties of the resulting film. It is quite evident that a need exists to improve emulsion polymer systems.

U.S. Pat. No. 4,151,143, issued to Blank et al., discloses a surfactant-free polymer emulsion coating composition and a method for preparing the same. Blank et al. identify that the main problem with emulsion polymers employed for coatings is the presence of surfactants which are employed to stabilize the emulsions but which adversely affect the water and corrosion resistance of the resulting film as well as the adhesion of the coating especially to metal surfaces. The Blank et al. emulsion polymers are prepared in a two stage process. The process includes (1) a first stage wherein a conventional carboxyl group containing polymer is prepared by a conventional solution or bulk polymerization technique and thereafter water-dispersed or solubilized by partial or full neutralization thereof with an organic amine or base and application of high shear agitation and (2) a second stage wherein a mixture of polymerizable monomers and polymerization catalyst is added to the first stage emulsion at an elevated temperature to effect polymerization of the stage two monomers resulting in the formation of an emulsion coating composition. The coating composition is surfactant-free.

U.S. Pat. No. 4,179,417, issued to Sunada et al., discloses a composition for water based paints containing a water-soluble resin and a water-dispersible polymer. The water soluble resin contains 50-99.5 percent by weight of an alpha,beta-monoethylenically unsaturated acid alkyl ester or an alkenyl benzene, 0.5-20 percent by weight of an alpha,beta-monoethylenically unsaturated acid and 0-30 percent by weight of an hydroxyalkyl ester of an alpha,beta-monoethylenically unsaturated acid. These monomers are polymerized in the presence of an alkyd resin containing a polymerizable unsaturated group, epoxy esters containing a polymerizable group, drying oils, fatty acids of drying oils and diene polymers. The resulting polymers are water solubilized by the addition of ammonia or an amine. The water-dispersible polymer contains hydroxy and/or carboxyl functional groups and contains an alpha,beta-monoethylenically unsaturated acid monomer and/or a hydroxy alkyl ester of such a monomer and other ethylenically unsaturated monomers. The compositions disclosed in U.S. Pat. No. 4,179,417 are employed as water based paints and can optionally contain a crosslinking agent.

Canadian Pat. No. 814,528, issued June 3, 1969, discloses low molecular weight alkali soluble resin, resin cuts and methods of their preparation and purification. The resins are disclosed as being especially useful as emulsifiers, leveling agents and film-formers. The number average molecular weight of the resins range from 700-5,000 and the resins have acid numbers between 140-300. The resins are disclosed as emulsifiers in the preparation of emulsion polymers resulting in emulsion polymers which are stable and substantially free from coagulum. For this use, i.e., emulsifier in emulsion polymerization reactions, the resins must have a number average molecular weight between 1,000 and 2,000 and preferably between 1,000 and 1,500. Resins having a number average molcular weight greater than 2,000 result in unstable and coagulated emulsion polymers when used as the emulsifier in emulsion polymerization reactions.

Problems commonly associated wtih high molecular weight emulsion polymers include problems relating to mechanical stability, freeze-thaw stability, viscosity, pigment dispersity and wetting. In particular, the viscosity of high molecular weight emulsion polymers is shear dependent (non-Newtonian) and shear thinning (decrease in viscosity) occurs.

The resin-fortified emulsion polymers of the present invention provide extraordinary mechanical, physical and performance properties when compared to conventional emulsion polymers and represent a pioneering advance in emulsion polymerization technology. In particular, the resin-fortified emulsion polymers of the present invention possess (1) substantially Newtonian-like rheological properties (viscosity is shear independent), (2) excellent mechanical stability and freeze-thaw stability, (3) excellent pigment dispersity and (4) excellent wetting properties. Additionally, the present invention allows great flexibility in controlling the amount and type of resin added to the emulsion polymer compared to the Blank et al. emulsion polymers and the polymers disclosed in Canadian Pat. No. 814,528. The greater flexibility allows for the control of the properties of the final emulsion polymer product.

SUMMARY OF INVENTION

Briefly, in accordance with the present invention, a resin-fortified emulsion polymer is prepared by adding a resin to an emulsion polymerization reaction mixture during the polymerization reaction. The resin is a low molecular weight polymer and is soluble or dispersible in water or alkali solutions. The emulsion polymerization reaction mixture contains any monomers employed in emulsion polymerization reactions. The resin is added to the reaction mixture during emulsion polymerization, i.e., after initiation of the emulsion polymerization reaction but before the polymerization reaction is substantially completed. The resulting resin-fortified emulsion polymers possess substantially Newtonian rheological properties, improved stability and good pigment dispersity and wetting properties.

The resins are added to the emulsion polymerization reaction mixture as solutions, solids (such as flakes or granules), or as slurries (suspension of solids in water). When the resin is added as a solid, either as a flake, granular or slurry, then an alkaline material is added to the reaction mixture in quantities sufficient to solubilize the resin. The monomer component of the emulsion polymerization reaction can be introduced into the reaction mixture all at once or portions of the monomer component can be added to the reaction mixture at various times, i.e., multi-stage monomer addition. In either case, the monomers are usually added to the reaction mixture slowly over a 1/2 hour to 2 hour period.

DETAILED DESCRIPTION OF THE INVENTION

When used herein the term "emulsion polymer" refers to any polymer prepared by emulsion polymerization. Such polymers are formed by the polymerization of one or more monomers capable of undergoing free radical emulsion polymerization. When used herein the term "resin" encompasses all low molecular weight resins of from about 500 to about 20,000, and preferably about 500 to 10,000, number average molecular weight which are soluble or dispersible in water or alkali.

In practicing the present invention, emulsion polymerization is conducted wherein a low molecular weight resin is added to an emulsion polymerization reaction mixture during the emulsion polymerization reaction. The resin is added to the emulsion polymerization reaction mixture after polymerization has been initiated but before the emulsion polymerization reaction is substantially complete. The resin can be added as a solid, a solution or slurry. The monomers employed in the emulsion polymerization reaction can be added to the reaction mixture in a single stage or, alternatively, can be added to the reaction mixture in a multi-stage addition.

In conducting the present emulsion polymerization reaction standard emulsion polymerization techniques are employed with the exception of the in situ resin addition. Standard nonionic and anionic surfactants are employed in the reaction. Advantageously, the reaction is conducted at an elevated temperature of from about 60° to 100° C., at ambient pressure and under an inert atmosphere such as nitrogen. The reaction mixture is maintained under agitation employing standard mixing techniques.

Before the resin is added to the emulsion polymerization reaction mixture there must be a polymeric (or steric) stabilizer present in the reaction mixture to prevent coagulation of the emulsion particles. The stabilizer can be any of the conventional nonionic surfactants such as ethoxylated alkylphenols including ethoxylated nonylphenol having at least 20 ethylene oxide units, ethoxylated octylphenol having at least 20 ethylene oxide units or, alternatively, functional monomers such as acrylic acid, methacrylic acid or polyethylene glycol monomethacrylate. The stabilizer is added to the reaction mixture prior to resin addition and usually in amounts of from about 1 to about 8 percent by weight of the reaction mixture and preferably from about 2 to about 4 weight percent.

The resins are added to the emulsion polymerization reaction mixture as solutions, solids (flakes or granules) or as slurries. When the resin is added as a solid then a sufficient amount of alkaline material must be added to the reaction mixture in order to solubilize the resin. The method of addition of the resin to the reaction mixture is not critical to the practice of the present invention and may be introduced into the reaction mixture all at once or in portions over time during the emulsion polymerization reaction.

The monomers employed in the emulsion polymerization are preferably added to the reaction mixture in two or more stages. Typically, a small amount of monomer mix is added to the water/surfactant mixture with agitation. Thereafter the initiator is added to the reaction mixture followed by the addition of another portion of the monomer mix and the steric stabilizer. The polymerization reaction is then allowed to start. After the polymerization reaction has started, the low molecular weight resin is then added to the reaction mixture. After the addition of the resin, the balance of the monomer mix is added to the reactor and the emulsion polymerization reaction is allowed to be completed.

Suitable low molecular weight support resins employed in the practice of the present invention include any solution or bulk polymerized polymers prepared from ethylenically unsaturated monomers such as olefins, mono vinylidene aromatics, alpha,beta-ethylenically unsaturated carboxylic acids and esters thereof and ethylenically unsaturated dicarboxylic anhydrides. They are known materials and are prepared employing standard solution polymerization techniques. Preferably, the support resins are prepared in accordance with the teachings of U.S. Pat. No. 4,414,370, U.S. Pat. No. 4,529,787 and U.S. Pat. No. 4,546,160, all of which are incorporated herein by reference.

Other suitable commercially available resins include water dispersed or water dispersible aliphatic polyurethanes such as Spensol L52, an aliphatic polyurethane commercially available from Spenser Kellogg, and water dispersible silicone ethylene oxide copolymers such as FF400, a water dispersible silicone-ethylene oxide copolymer commercially available from Dow Corning. These and other similar resins can be used especially where the desirable characteristics of the resin, i.e., flexibility, slip properties, durability, etc., are required. These resins should be low molecular weight with a number average molecular weight of from about 5,000 to 20,000.

Suitable monomers employed in the preparation of the support resins include acrylic acid, methacrylic acid, styrene, alpha-methylstyrene, hydroxyethylmethacrylate and esters of acrylic acid and methacrylic acid.

Preferred support resins include those resins containing styrene (ST), alpha methylstyrene (AMS), acrylic acid (AA) and mixtures thereof. An especially preferred support resin is a ST/AA copolymer containing three parts ST and one part AA, and which has a number average molecular weight of from about 1,000 to about 6,000, and preferably from about 2,000 to about 4,000.

The monomers employed in the preparation of the present emulsion polymers are any monomers used in emulsion polymerization reactions. Suitable monomers include ethylenically unsaturated monomers such as olefins, mono vinylidene aromatics, alpha,beta-ethylenically unsaturated carboxylic acids and esters thereof, ethylenically unsaturated dicarboxylic anhydrides and halo substituted olefinics. Suitable monomers include styrene (ST), alpha methylstyrene (AMS), acrylic acid (AA), methacrylic acid (MAA), methylmethacrylate (MMA), butylmethacrylate (BMA), butylacrylate (BA), 2-ethylhexylacrylate (2-EHA), ethylacrylate (EA), hydroxyethylacrylate (HEA), and hydroxyethylmethacrylate (HEMA).

As noted above, the resins useful in the process of the present invention should be low molecular weight with a number average molecular weight in the range of from about 500 to about 20,000, preferably about 500 to about 10,000 and optimally about 2,000 to about 4,000. Also the resins must be water soluble or water dispersible either as is or in an alkaline medium such as ammonium hydroxide.

In one embodiment of the present invention, water and a sufficient amount of surfactant are added to a reactor under an inert atmosphere and brought to reaction temperature.

The monomer mixture and the initiator are then co-fed into the reactor with agitation. The monomer mixture may be added all at once or, alternatively, it can be fed into the reactor over an extended period of time, i.e., 1-2 hours. After the initiator addition, a low molecular weight resin is then added to the reaction mixture during the polymerization process. The resin can be added to the reaction mixture as a solid or a solution. When the resin is added as a solid, an alkali (aqueous NH₄ OH) is added to the reaction mixture with the solid resin or after the addition of the solid resin. The time at which the support resin is added to the reaction mixture is not critical to the practice of the present invention, however, it is preferred that the reaction of the monomers be at least about 30%, preferably about 30 to 50%, complete before the resin is added to the reaction mixture. The support resin can be added immediately after the addition of the initiator and anytime up to an hour after the monomer mixture and initiator have been added to the reaction mixture.

In another embodiment of the present invention, water and sufficient amount of surfactant are added to a reactor under an inert atmosphere and brought to reaction temperature. A minor portion (0.1-15% by weight) of the monomer mixture to be used in the emulsion polymerization reaction is added to the reactor followed by the addition of an initiator. A second portion (25-90 weight percent) of the monomer mixture is then added slowly over a 1 to 2 hour perod to the reaction mixture. After the addition of this second portion of monomer, the support resin is added to the reaction mixture as either a solid or a solution. After the addition of the resin, a third portion (5-75 percent by weight) of the monomer mixture is added slowly to the reaction mixture over a 1/4 to 1 hour period. If the support resin is added as a solid, then aqueous alkali is simultaneously added to the reactor during the addition of the third portion of monomer mixture. The reaction is then added at reaction temperature with agitation for an additional 1 to 2 hour period.

In another embodiment of the present invention, water and a sufficient amount of surfactant are added to a reactor under an inert atmosphere and brought to the reaction temperature. A minor portion (1/50-1/10) of the monomer mixture is added to the reactor followed by the addition of an initiator. The reaction is held for 5 minutes and then the balance of the monomer mixture is slowly added to the reactor over a 1 to 2 hour period. A support resin is then added to the reaction mixture anytime up to an hour after all of the monomer mixture has been added to the reactor. If the support resin is added as a solid, then a sufficient amount of alkali must be added to the reaction mixture to solubilize the solid resin. The reaction mixture is then held for an additional one to two hours at elevated temperature.

For those embodiments where the resin and alkali are added with some of the monomers, the precharge should contain all of the monomers, i.e., acid containing monomers such as acrylic acid which will be solubilized by the alkali. If this is not done, the acid functional monomer may go into the aqueous phase and will not be available for reaction with the monomers which are not water soluble.

The support resin is added to the present emulsion polymerization reaction in amounts sufficient to modify the flow characteristics of the resulting emulsion polymer. Amounts ranging from about 2 to about 50 weight percent or more based on the total weight of solids in the emulsion polymerization reaction mixture are usually effective. Advantageously the support resin is added in amounts greater than about 5% and preferably greater than about 10% by total weight of solids in the emulsion reaction mixture. The optimum amount of support resin to be added during the emulsion polymerization reaction will depend on a variety of factors, such as the particular makeup of the support resin, the particular makeup of the emulsion polymer, the end use application for the emulsion polymer, and the environment in which the emulsion polymer will be used. One skilled in the art can readily determine the optimum amount of support resin to be used in a particular application by conducting routine experiments.

The following examples illustrate the practice of the present invention but should not be construed as limiting its scope.

EXAMPLE 1 Support Resin Preparation

The following support resins were prepared employing the bulk polymerization process described in U.S. Pat. No. 4,529,787. The monomer content, number average molecular weight (Mn) and the weight average molecular weight are listed below:

    ______________________________________                                         Monomers*      Monomer Ratio  Mn**    Mw                                       ______________________________________                                         Resin A                                                                               ST/AMS/AA   62ST/21AMS/17AA                                                                               1740  3605                                   Resin B                                                                               ST/AA       75ST/25AA      3270  8360                                   Resin C                                                                               ST/AMS/AA   31ST/37AMS/32AA                                                                               3040  8430                                   Resin D                                                                               ST/AMS/AA   42ST/21AMS/37AA                                                                               2060  4880                                   ______________________________________                                          *ST = styrene, AMS = alpha methylstyrene, AA = acrylic acid                    Mn** Molecular weight was determined by gel permeation chromatography          (GPC) using polystyrene as the standard.                                 

EXAMPLE 2 Resin-Fortified Emulsion Polymer 1-5

The Items A (water, surfactant), B (water, initiator), C (monomer mixture), D (resins from Example 1), E (monomer mixture), and F (aqueous NH₄ OH) listed in Table 1 below were prepared by admixing the components of each item. Items A, B, C and E were purged with N₂ for over six (6) minutes. The resin-fortified emulsion polymers 1-5 were prepared by adding Item A to a reactor, and heating to a temperature of 80° C. under a low stream of N₂. Ten (10) grams (g) of Item C were added to the reactor and stirred for one (1) minute. Item B (initiator) was added to the reactor with stirring. Four (4) minutes after the addition of Item B, the balance of Item C was added to the reactor over 40-60 minutes. Item D (resin) was added to the reactor with stirring. One minute after the addition of Item D, Items E and F were simultaneously added to the reactor with stirring. Item E was added over a 40-60 minute period, while Item F was added over a 20-30 minute period. After Item E was added to the reactor, the reaction was maintained for an additional 40 minute period. The reaction mixture was cooled to room temperature and filtered through cheesecloth.

                                      TABLE 1                                      __________________________________________________________________________     ITEMS (Components* in grams)                                                   __________________________________________________________________________     Resin-Fortified                                                                          A          B      C                                                  Emulsion Polymer                                                                         H.sub.2 O                                                                         TX100                                                                              NaLS                                                                               H.sub.2 O                                                                         *APS                                                                               ST                                                                               MMA 2EHA                                                                               BMA BA MAA AA TX100                      __________________________________________________________________________     1         331                                                                               0.56                                                                               2.80                                                                               36.8                                                                              1.12                                                                               84                                                                               65.1                                                                               58.9                                                                               --  -- 10.6                                                                               -- --                         2         380                                                                               0.50                                                                               3.0 30 1.2 --                                                                               --  --  230 -- 8   -- --                         3         380                                                                               0.50                                                                               3.0 30 1.2 --                                                                               --  --  230 -- 8   -- --                         4         380                                                                               0.56                                                                               3.5 30 1.2 --                                                                               196 --  --  49 4   -- --                         5         270                                                                               --  3.0 20 1.4 32                                                                               64  --  --  64 1.6 1.2                                                                               3.0                        __________________________________________________________________________     Resin-Fortified D           E                  F                               Emulsion Polymer                                                                               RESIN B                                                                              RESIN A                                                                              ST  MMA 2EHA                                                                               BMA BA H.sub.2 O                                                                          NH.sub.4 OH                 __________________________________________________________________________     1               64    --    36.8                                                                               28.5                                                                               25.7                                                                               --  -- 34.0                                                                               16.8                        2               35    --    --  --  --  120 -- 20  12                          3               8.75  --    --  --  --  120 -- 20  6.8                         4               17    --    --  80  --  --  20 20  8                           5               96    25.6  160 --  --  --  -- 110 16                          __________________________________________________________________________      *APS = Ammonium persulfate                                                     TX100 = TRITON X100                                                            NaLS = sodium lauryl sulfate                                                   ST = Styrene                                                                   MMA = methyl methacrylate                                                      2EHA = 2 ethylhexylacrylate                                                    BA = butyl acrylate                                                            MAA = methacrylic acid                                                         AA = acrylic acid                                                        

EXAMPLE 3 Resin-Fortified Emulsion Polymers 6 & 7

The Items A (water, surfactant), B (water, initiator), C (monomer), D (water, surfactant), E (monomer), F (resins from Example 1) and G (aqueous NH₄ OH) listed in Table 2 below were prepared by admixing the components of each item. Items A, B, C and E were purged with N₂ for six (6) minutes. The resin-fortified emulsion polymers 6 and 7 were prepared by adding Item A into a reactor and heating to a temperature of 80° C. under a slow stream of N₂. Ten (10) g of Item C were added to the reactor and stirred for one minute. Item B was added to the reactor. Five (5 ) minutes after the addition of Item B, Item D and 20 g of Item C were simultaneously added to the reactor over a 7-10 minute period. Item E was then added to the reactor over a 50-60 minute period. Then Item F (the resin) was added to the reactor followed one minute later with the addition of Items C and G. Item C was added over a 30-50 minute perod while Item G was added over a 20-30 minute period. After all of Item C was added to the reactor, the reaction mixture was maintained at 80° C. with stirring for an additional 40 minutes. The reaction mixture was cooled to room temperature and filtered through cheesecloth.

                                      TABLE 2                                      __________________________________________________________________________     ITEMS (Components* in grams)                                                   __________________________________________________________________________     Resin-Fortified                                                                          A      B     C          D                                            Emulsion Polymer                                                                         H.sub.2 O                                                                         DS10                                                                               H.sub.2 O                                                                         APS                                                                               MMA ST 2EHA                                                                               H.sub.2 O                                                                         NaSS                                                                               TX100                                 __________________________________________________________________________     6         350                                                                               3.5 30 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               35 0.6 1.0                                   7         350                                                                               3.5 30 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               35 0.6 1.0                                   __________________________________________________________________________     Resin-Fortified                                                                          E                F         G                                         Emulsion Polymer                                                                         MMA ST  2EHA                                                                               HEM10                                                                               Resin B                                                                             Resin A                                                                             H.sub.2 O                                                                         NH.sub.4 OH                            __________________________________________________________________________     6         62.8                                                                               80.8                                                                               56.5                                                                               8    37.4 --   30 13                                     7         62.8                                                                               80.8                                                                               56.5                                                                               8    --   37.4 30 13                                     __________________________________________________________________________      *DS10 = sodium nonylphenyl sulfonate                                           NaSS = sodium styryl sulfonate                                                 HEM10 = polyethylene glycol monomethacrylate (10 moles PEG) ALCOLAC      

EXAMPLE 4 Resin-Fortified Emulsion Polymers 8-11

The Items A (water, surfactant), B (water, initiator), C (monomers), D (water, surfactant), E (monomers) and F (resin solution) listed in Table 3 below were prepared by admixing the components of each item. The resin solution was the resin listed plus deionized water and sufficient ammonium hydroxide to bring the pH to about 9 to solubilize the resin. Items A, B, C, D and E were purged with N₂ for over 6 minutes. The resin-fortified emulsion polymers 8-11 were prepared by adding Item A to a reactor and heating to 80° C. under a slow stream of N₂. Ten (10) g of Item C were added to the reactor with stirring and after one minute Item B were added to the reactor. Five (5) minutes after the addition of Item B, Item D and 20 g of Item C were simultaneously added to the reactor over a 7-10 minute period. Item E was then added to the reactor over a 50-60 minute period. After the addition of Item E, Items C and F were simultaneously added to the reactor. Item C was added to the reactor over a 30-50 minute period while Item F was added to the reactor over a 20-30 minute period. After all of Item C was added to the reactor, the reaction mixture was maintained at 80° C. with stirring for an additional 40 minutes. The reaction mixture was cooled to room temperature and filtered through cheesecloth.

                                      TABLE 3                                      __________________________________________________________________________     ITEMS (Components* in grams)                                                   __________________________________________________________________________     Resin-fortified                                                                          A          B     C          D                                        Emulsion Polymer                                                                         H.sub.2 O                                                                         TX100                                                                              DX10                                                                               H.sub.2 O                                                                         APS                                                                               MMA ST 2EHA                                                                               H.sub.2 O                                                                         NaSS                                  __________________________________________________________________________      8        310                                                                               0.5 2.5 40 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               40 0.6                                    9        310                                                                               0.5 2.5 40 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               40 0.6                                   10        310                                                                               0.5 2.5 40 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               40 0.6                                   11        310                                                                               0.5 30  30 1.3                                                                               50.2                                                                               64.6                                                                              45.2                                                                               40 0.6                                   __________________________________________________________________________     Resin-fortified                                                                          E                   F                                                Emulsion Polymer                                                                         MMA ST 2EHA                                                                               HEM10                                                                               HEM5                                                                               Resin                                                                              Ammonium Solutions                           __________________________________________________________________________      8        62.8                                                                               80.8                                                                              56.5                                                                               6    --  80  (Resin A; 11.3% solid)                        9        62.8                                                                               80.8                                                                              56.5                                                                               6    --  80  (Resin C; 11.3% solid)                       10        62.8                                                                               80.8                                                                              56.5                                                                               6    --  80  (Resin D; 11.3% solid)                       11        62.8                                                                               80.8                                                                              56.5                                                                               --   12  100 (Resin B; 30% solid)                         __________________________________________________________________________

EXAMPLE 5 Resin-Fortified Emulsion Polymers 12-15

The Items A (water, surfactant), B (water, initiator), C (monomers), D (monomers), E (resin solution, NH₄ OH) and F (styrene) listed in Table 4 below, were prepared by admixing the components of each item. Items A, B, C, D and F were purged with N₂ for over 6 minutes. Resin-fortified emulsion polymers 12-15 were prepared by adding Item A to a reactor and heating to a temperature of 80° C. under a slow stream of N₂. Ten (10) g of Item C were added to the reactor with stirring, and then one minute later Item B was added. Four minutes after the addition of Item B, the rest of Item C was added to the reactor over a 15-20 minute period. Item D was then added to the reactor over a 30-35 minute period. Five minutes after the addition of Item D, Items E and F were simultaneously added to the reactor. Item E was added to the reactor over a 30-35 minute period, while Item F was added over a 40-50 minute period. The reaction mixture was maintained at 80° C. with stirring for 40 minutes after all of Item F had been added to the reactor. The reaction mixture was then cooled to room temperature and filtered through cheesecloth.

                                      TABLE 4                                      __________________________________________________________________________     ITEMS (Components* in grams)                                                   __________________________________________________________________________     Resin-Fortified                                                                          A      B     C           D                                           Emulsion Polymers                                                                        H.sub.2 O                                                                         NaLS                                                                               H.sub.2 O                                                                         APS                                                                               MONOMERS*                                                                              MAA MONOMERS*                                                                              MAA HEM5                            __________________________________________________________________________     12        260                                                                               30  16 1.4                                                                               60      1.8 100     11  5                               13        260                                                                               30  16 1.4                                                                               60      1.8 100     11  5                               14        260                                                                               30  16 1.4                                                                               60      1.8 100     11  5                               15        260                                                                               30  16 1.4                                                                               60      1.8 100     11  5                               __________________________________________________________________________                        Resin-Fortified                                                                          E                  F                                                 Emulsion Polymers                                                                        RESIN                                                                               SOLUTION NH.sub.4 OH                                                                         ST                             __________________________________________________________________________                        12        156  (Resin C; 20.5%)                                                                        5    160                                               13        156  (Resin B; 20.5%)                                                                        5    160                                               14        156  (Resin D; 20.5%)                                                                        5    160                                               15        237  (Resin A; 13.5%)                                                                        5    160                            __________________________________________________________________________      *Monomers = MMA/St/BA/EA/TX100 = 20/50/20/10/1.8 (Wt. %)                 

EXAMPLE 6 Resin-Fortified Emulsion Polymer 16-20

The Items A (water, surfactant), B (water, initiator), C (monomers with stabilizer), D (resin), E (monomers) and F (aqueous NH₄ OH) listed in Table 5 below were prepared by admixing the components of each item. Items A, B, C and E were purged with N₂ for 6 minutes. The resin-fortified emulsion polymers 16-20 were prepared by adding Item A to a reactor and heating to a temperature between 75° C. and 80° C. under a slow stream of N₂. One-twentieth (1/20) of Item C was added to the reactor, with stirring, followed by the addition of Item B to initiate the polymerization reaction. Five (5) minutes after the addition of Item B, the balance of Item C was added to the reactor over a 1/2 hour period. Items D, E, and F, when F was employed, were added to the reactor in three different procedures as follows:

Procedure 1: For resin-fortified emulsions 16 and 18, Item D was added to the reactor as solid flakes. Items E and F were simultaneously added to the rector over a 1/2 hour period. The reaction was then allowed to continue for one hour at 75°-80° C. with stirring.

Procedure 2: for resin-fortified emulsions 17 and 19, Items E and D were simultaneously added to the reactor over a 1/2 hour period. The reaction was then allowed to continue for one hour at 75°-80° C. with stirring.

Procedure 3: For resin-fortified emulsion 20, Item D (flakes) was added to the reactor 40 minutes after the addition of all of Item C. Item F was then added to the reactor over a 1/2 hour period. The reaction was allowed to continue for one hour at 60° C. with stirring.

                                      TABLE 5                                      __________________________________________________________________________     ITEMS (Components* in grams)                                                   __________________________________________________________________________     Resin-Fortified                                                                          A                    B     C                                         Emulsion Polymer                                                                         H.sub.2 O                                                                         TX100                                                                               NaLS                                                                               DS10 NaSS                                                                               H.sub.2 O                                                                         APS                                                                               MONOMERS                                                                               MAA HEM10                                                                               HEM20                                                                               TX100               __________________________________________________________________________     16        41.4                                                                              0.07 0.35                                                                               --   --  4.61                                                                              0.140                                                                             26.0    1.33                                                                               --   --   --                  17        42.45                                                                             0.07 0.438                                                                              --   --  3.753                                                                             0.150                                                                             27.53   0.751                                                                              --   --   0.375               18        40.29                                                                             0.06 --  0.476                                                                               0.077                                                                              3.574                                                                             0.154                                                                             27.4    --  0.714                                                                               --   --                  19        37.62                                                                             0.057                                                                               --  0.342                                                                               0.068                                                                              3.42                                                                              0.148                                                                             21.65   --  0.912                                                                               --   --                  20        46.55                                                                             0.059                                                                               --  0.591                                                                                0.0829                                                                            3.555                                                                             0.213                                                                             33.79   --  --   0.711                                                                               --                  __________________________________________________________________________                                        D                                                                    Resin-Fortified                                                                          RESIN    E       F                                                   Emulsion Polymer                                                                         (from Example 1)                                                                        MONOMERS                                                                               H.sub.2 O                                                                         NH.sub.4 OH             __________________________________________________________________________                                                            (28%)                                            16        B 8.0 (flake)                                                                           11.4    4.26                                                                              2.11                                             17        A 9.41 (23% sol.)                                                                       15.01   -- --                                               18        D 2.40 (flake)                                                                          23.83   -- 0.83                                             19        A 21.0 (17% sol.)                                                                       19.38   -- --                                               20        C 12.0 (flake)                                                                          3.55    -- 3.7                     __________________________________________________________________________      *DS10 = Siponate DS 10                                                         NaSS = Spinomer Na SS                                                          Monomers = Polymer of ST/MMA/BA/BMA/2EHA/EA                                    HEM10 = Polyethylene glycol monomethacrylate (20 moles PEG)              

EXAMPLE 7

A resin cut having the following formulation was prepared:

    ______________________________________                                         Resin Cut A                                                                                         Parts by Weight                                           ______________________________________                                         Deionized Water        74.516                                                  Ethoxylated octylphenol (40 moles                                                                     1.652                                                   ethylene oxide) Triton X-405 (70%                                              solids)                                                                        Ammonium Hydroxide     3.188                                                   Resin A Flakes (Example 1)                                                                            16.515                                                  Resin B Flakes (Example 1)                                                                            4.129                                                                          100.000                                                 ______________________________________                                          Z

Resin Cut A was prepared by charging the water, Triton X-405 and ammonium hydroxide into a vessel at ambient temperature. The Resin A and B Flakes were sifted in with moderate agitation. The temperature was raised to 70° C. and increased agitation when the mixture reaches 70° C. Hold with agitation for about 30 minutes at 70° C. Cool to less than 37° C. and filter. Store in a sealed container to prevent ammonia loss.

An emulsion polymer having the following components was prepared:

    ______________________________________                                                             Parts by Weight                                            ______________________________________                                         Initial Flask Charge:                                                          Deionized Water       22.978                                                   Sodium Lauryl Sulfate (15% Actives)                                                                  2.182                                                    Ethoxylated Octylphenol (10 moles                                                                    0.245                                                    ethylene oxide) (Triton X-100)                                                                       25.405                                                   Ammonium Persulfate Charge:                                                    Deionized Water       1.608                                                    Ammonium Persulfate   0.225                                                                          1.823                                                    First Stage Monomer Charge:                                                    Styrene               5.402                                                    Methylmethacrylate    1.688                                                    Butylacrylate         1.351                                                    Methacrylic Acid      0.717                                                                          9.158                                                    Resin Cut A (21.8% Solids)                                                                           29.727                                                   Second Stage Monomer Charge:                                                   Styrene               20.322                                                   Methylmethacrylate    6.351                                                    Butylacrylate         5.081                                                                          31.754                                                   Post Hold Ammonia Charge:                                                      Deionized Water       1.608                                                    Ammonium Hydroxide    0.505                                                                          2.113                                                    Preservative (Kathon LX-14)                                                                          0.010                                                                          100.000                                                  ______________________________________                                    

The Initial Flask Charge was heated to 79° C. with mild agitation and a mild nitrogen purge. About 10% of the First Stage Monomer Charge was added, followed immediately by the Ammonium Persulfate Charge. This was held for about 20 minutes to build a radical flux. The remaining First Stage Monomer Charge was added incrementally over about 30 minutes, followed by a 10 minute hold. Resin Cut A was then added incrementally over about 30 minutes, and was followed immediately by the addition of the Second Stage Monomer Charge incrementally over about 80 minutes. Agitation was increased 25-50% during the last 25 minutes of the Second Stage Monomer Charge addition. After all monomers were added, the mixture was held for about 60 minutes. At this point, the Post Hold Ammonia Charge was added and the mixture was cooled to 37° C. The pH should be in the range of 9.3 to 9.6. The preservative was then added and the product was filled into suitable containers.

EXAMPLE 8

The following emulsion polymer was prepared:

    ______________________________________                                         A:   Deionized Water          90      g                                             Sodium Lauryl Sulfate    1.2     g                                        B:   Deionized Water          20      g                                             Ammonium Persulfate      0.8     g                                        C:   Methylmethacrylate       23.5    g                                             Styrene                  30.3    g                                             2-Ethylhexylacrylate     21.2    g                                             Ethoxylated Octylphenol (10 moles ethy-                                                                 2.25    g                                             lene oxide) (Triton X-100-100% solids)                                         Methacrylic Acid         4.5     g                                        D:   Deionized Water          20      g                                             Ammonium Hydroxide (28%) 6       g                                        E:   Methylmethacrylate       23.5    g                                             Styrene                  30.3    g                                             2-Ethylhexylacrylate     21.2    g                                        F:   Resin B Aqueous Ammonia Cut                                                                             85      g                                             (18.29% solids) (pH = 9)                                                  ______________________________________                                          Each of Items A through F were prepared by mixing the components and      purging with nitrogen for 6 minutes. Solution F includes sufficient Resin      B, deionized water and ammonium hydroxide to produce a 18.29% solution (of      Resin B) at a pH of 9. Item A was added to the reaction and heated to      80° C. under a slow stream of nitrogen. 10 g of Item C were added      to the reactor and stirred for 1 minute. Then Item B was added and the      reaction was held for 10 minutes. The rest of Item C was added over 25 to      30 minutes. This was followed by addition of Item D over 5 minutes and      held for 5 minutes. Items E and F were added simultaneously over a period      of 40-50 minutes for Item E and 25-35 minutes for Item F. After Item E was      added, the reaction was held for one hour at 80° C. and then cooled      to room temperature and filtered.

Similar resin-fortified emulsion polymers are prepared when various monomers are employed in an emulsion polymerization reaction when various support resins, described herein, are added to the emulsion polymerization reaction mixture during the polymerization reaction. The resulting resin-fortified emulsion polymers possess substantially Newtonian-like rheological characteristics. These resin-fortified polymers are also stable and have good pigment dispersity and wetting characteristics.

The resin-fortified emulsion polymers of the present invention are useful in any of the standard applications for emulsion polymers. Typical use applications for the present resin-fortified emulsion polymers includes coatings and graphic arts.

Of particular interest in the practice of the present invention, the resin-fortified emulsion polymer described in Example 7 is employed as a formaldehyde-free coating for wood. The emulsion polymer is applied to the wood substrate employing standard application techniques. 

It is claimed:
 1. A method for producing a resin-fortified polymer emulsion having Newtonian-like flow characteristics, utilizing an emulsion-polymerization reaction, wherein particles of an emulsion-polymer product form in the emulsion as a result of the utilization of the emulsion-polymerization reaction, the method comprising the steps of:adding, to a reactor means, water and a first portion of a surfactant stabilizer, wherein the surfactant stabilizer is present in an amount effective for preventing coagulation of the emulsion-polymer product particles; agitating the reactor contents, and subjecting the agitated reactor contents to an inert atmosphere; heating the agitated reactor contents to a predetermined reaction temperature; adding to the agitated-and-heated reactor contents a first portion of an emulsion-polymerizable monomer mixture comprising ethylenically-unsaturated emulsion-polymerizable monomers selected from the group consisting of olefins, monovinylidene aromatics, alpha,beta-ethylenically unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated carboxylic anhydrides, halo substituted olefinics, and combinations thereof; adding to the emulsion-polymerizable monomer-containing agitated-and-heated reactor contents an effective amount of an initiator for initiating the emulsion-polymerization reaction; adding to the initiator-containing agitated-and-heated reactor contents a second portion of the emulsion-polymerizable monomer mixture together with the remainder amount of the surfactant stabilizer; thereafter adding to the agitated-and-heated reactor contents a polymeric resin, soluble or dispersible in water or in alkali, said resin having been produced either by a solution-polymerization method or by a bulk-polymerization method, wherein the polymeric resin is produced from at least one ethylenically-unsaturated monomer selected from the group consisting of olefins, mono vinylidene aromatics, alpha beta ethylenically-unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, and mixtures thereof; and adding to the polymeric resin-containing agitated reactor contents the remainder of the emulsion-polymerizable monomer mixture.
 2. The method of claim 1 wherein the surfactant stabilizer is selected from the group consisting of a nonionic surfactant and an acrylic-based functional monomer.
 3. The method of claim 2 wherein the nonionic surfactant is an ethoxylated alkylphenol selected from the group consisting of nonylphenol and octylphenol, each said ethoxylated alkylphenol having at least 20 ethylene oxide units.
 4. The method of claim 2 wherein the acrylic-based functional monomer is selected from the group consisting of acrylic acid, methacrylic acid, polyethylene glycol monomethacrylate, and combinations thereof.
 5. The method of claim 2 wherein the acrylic-based functional monomer is methacrylic acid.
 6. The method of claim 1 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 1 to about 8 weight percent, based upon the weight of the reactor contents.
 7. The method of claim 1 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 2 to 4 weight percent, based upon the weight of the reactor contents.
 8. The method of claim 1 wherein the predetermined reaction temperature is about 60° to about 100° C., and wherein the inert atmosphere is nitrogen.
 9. The method of claim 1 wherein the ethylenically unsaturated monomers of the emulsion-polymerizable monomer mixture are selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, and combinations thereof.
 10. The method of claim 1 wherein the polymeric resin is present in an amount of about 2 to more than about 50 weight percent, based on the weight of the reactor contents.
 11. The method of claim 1 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of acrylic acid, methacrylic acid, styrene, alpha-methyl styrene, hydroxyethyl methacrylate, esters of acrylic acid and methacrylic acid, and mixtures thereof.
 12. The method of claim 1 wherein the ethylenically-unsaturated monomer utlized to make the polymeric resin is selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, and mixtures thereof.
 13. The method of claim 12 wherein the polymeric resin is a copolymer of styrene and acrylic acid and has a number-average molecular weight of about 1,000 to about 6,000.
 14. The method of claim 13 wherein the copolymer of the polymeric resin comprises three weight-parts styrene and one weight-part acrylic acid.
 15. The method of claim 14 wherein the number-average molecular weight of the copolymer is about 2,000 to about 4,000.
 16. A method for producing a polymer emulsion having Newtonian-like flow characteristics, utilizing an emulsion-polymerization reaction, wherein particles of an emulsion-polymer product form in the emulsion as a result of the utilization of the emulstion-polymerization reaction, the method comprising the steps of:adding, to a reactor means, water and an effective amount of a surfactant stabilizer for preventing coagulation of the emulsion-polymer product particles; agitating the reactor contents, and subjecting the agitated reactor contents to an inert atmosphere; heating the agitated reactor contents to a predetermined reaction temperature; co-feeding into the reactor means (1) an emulsion-polymerizable monomer mixture comprising ethylenically-unsaturated emulsion-polymerizable monomers selected from the group consisting of olefins, monovinylidene aromatics, alpha,beta-ethylenically unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, halo substituted olefinics, and combinations thereof, and (2) an effective amount of an initiator for initiating the emulsion-polymerization reaction; and adding to the agitated-and-heated reactor contents, after initiation but prior to completion of the emulsion-polymerization reaction, a polymeric resin, soluble or dispersible in water or in alkali, said resin having been produced either by a solution-polymerization method or by a bulk-polymerization method, wherein the polymeric resin is produced from at least one ethylenically-unsaturated monomer selected from the group consisting of olefins, mono vinylidene aromatics, alpha beta ethylenically-unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, and mixtures thereof.
 17. The method of claim 16 wherein the surfactant stabilizer is selected from the group consisting of a nonionic surfactant and an acrylic-based functional monomer.
 18. The method of claim 17 wherein the nonionic surfactant is an ethoxylated alkylphenol selected from the group consisting of nonylphenol and octylphenol, each said ethoxylated alkylphenol having at least 20 ethylene oxide units.
 19. The method of claim 17 wherein the acrylic-based functional monomer is selected from the group consisting of acrylic acid, methacrylic acid, polyethylene glycol monomethacrylate, and combinations thereof.
 20. The method of claim 17 wherein the acrylic-based functional monomer is methacrylic acid.
 21. The method of claim 16 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 1 to about 8 weight percent, based upon the weight of the reactor contents.
 22. The method of claim 16 wherein the surfacfant stabilizer is present in the reactor contents in an amount of from about 2 to 4 weight percent, based upon the weight of the reactor contents.
 23. The method of claim 16 wherein the predetermined reaction temperature is about 60° to about 100° C., and wherein the inert atmosphere is nitrogen.
 24. The method of claim 16 wherein the ethylenically unsaturated monomers of the emulsion-polymerizable monomer mixture are selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, and combinations thereof.
 25. The method of claim 16 wherein the polymeric resin is present in an amount of about 2 to more than about 50 weight percent, based on the weight of the reactor contents.
 26. The method of claim 16 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of acrylic acid, methacrylic acid, styrene, alpha-methyl styrene, hydroxyethyl methacrylate, esters of acrylic acid and methacrylic acid, and mixtures thereof.
 27. The method of claim 16 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, and mixtures thereof.
 28. The method of claim 27 wherein the polymeric resin is a copolymer of styrene and acrylic acid and has a number-average molecular weight of about 1,000 to about 6,000.
 29. The method of claim 28 wherein the copolymer of the polymeric resin comprises three weight-parts styrene and one weight-part acrylic acid.
 30. The method of claim 29 wherein the number-average molecular weight of the copolymer is about 2,000 to about 4,000.
 31. A method for producing a resin-fortified polymer emulsion having Newtonian-like flow characteristics, utilizing an emulsion-polymerization reaction, wherein particles of an emulsian-polymer product form as a result of the utilization of the emulsion-polymerization reaction, the method comprising the steps of:adding, to a reactor means, water and an effective amount of a surfactant stabilizer for preventing coagulation of the emulsion-polymer product particles; agitating the reactor contents, and subjecting the agitated reactor contents to an inert atmosphere; heating the agitated reactor contents to a predetermined reaction temperature; adding to the agitated-and-heated reactor contents a first portion of an emulsion-polymerizable monomer mixture comprising ethylenically-unsaturated emulsion-polymerizable monomers selected from the group consisting of olefins, monovinylidene aromatics, alpha,beta-ethylenically unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, halo substituted olefinics, and combinations thereof; adding to the emulsion-polymerizable monomer-containing agitated-and-heated reactor contents an effective amount of an initiator for initiating the emulsion polymerization reaction; adding to the initiator-containing agitated-and-heated reactor contents, a second portion of the emulsion-polymerizable monomer mixture; thereafter adding to the agitated-and-heated reactor contents a polymeric resin, soluble or dispersible in water or in alkali, said resin having been produced either by a solution-polymerization method or by a bulk-polymerization method, wherein the polymeric resin is produced from at least one ethylenically-unsaturated monomer selected from the group consisting of olefins, mono vinylidene aromatics, alpha beta ethylenically-unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, and mixtures thereof; adding, after completion of the polymeric resin-addition step, the remainder of the emulsion-polymerizable monomer mixture to the agitated-and-heated reactor contents; and thereafter maintaining the reactor contents at the reaction temperature, with agitation, for a predetermined period of time.
 32. The method of claim 31 wherein the surfactant stabilizer is selected from the group consisting of a nonionic surfactant and an acrylic-based functional monomer.
 33. The method of claim 32 wherein the nonionic surfactant is an ethoxylated alkylphenol selected from the group consisting of nonylphenol and octylphenol, each said ethoxylated alkylphenol having at least 20 ethylene oxide units.
 34. The method of claim 32 wherein the acrylic-based functional monomer is selected from the group consisting of acrylic acid, methacrylic acid, polyethylene glycol monomethacrylate, and combinations thereof.
 35. The method of claim 32 wherein the acrylic-based functional monomer is methacrylic acid.
 36. The method of claim 31 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 1 to about 8 weight percent, based upon the weight of the reactor contents.
 37. The method of claim 31 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 2 to 4 weight percent, based upon the weight of the reactor contents.
 38. The method of claim 31 wherein the predetermined reaction temperature is about 60° to about 100° C., and wherein the inert atmosphere is nitrogen.
 39. The method of claim 31 wherein the ethylenically unsaturated monomers of the emulsion-polymerizable monomer mixture are selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, and combinations thereof.
 40. The method of claim 31 wherein the polymeric resin is present in an amount of about 2 to more than about 50 weight percent, based on the weight of the reactor contents.
 41. The method of claim 31 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of acrylic acid, methacrylic acid, styrene, alpha-methyl styrene, hydroxyethyl methacrylate, esters of acrylic acid and methacrylic acid, and mixtures thereof.
 42. The method of claim 31 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, and mixtures thereof.
 43. The method of claim 42 wherein the polymeric resin is a copolymer of styrene and acrylic acid and has a number-average molecular weight of about 1,000 to about 6,000.
 44. The method of claim 43 wherein the copolymer of the polymeric resin comprises three weight-parts styrene and one weight-part acrylic acid.
 45. The method of claim 44 wherein the number-average molecular weight of the copolymer is about 2,000 to about 4,000.
 46. A method for producing a resin-fortified polymer emulsion having Newtonian-like flow characteristics, utilizing an emulsion-polymerization reaction, wherein particles of an emulsion-polymer product form in the emulsion as a result of the utilization of the emulsion-polymerization reaction, the method comprising the steps of:adding, to a reactor means, water and an effective amount of a surfactant stabilizer for preventing coagulation of the emulsion-polymer product particles; agitating the reactor contents, and subjecting the agitated reactor contents to an inert atmosphere; heating the agitated reactor contents to a predetermined reaction temperature; adding to the agitated-and-heated reactor contents a minor portion of an emulsion-polymerizable monomer mixture comprising ethylenically-unsaturated emulsion-polymerizable monomers selected from the group consisting of olefins, monovinylidene aromatics, alpha, beta-ethylenically unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, halo substituted olefinics, and combinations thereof; thereafter adding to the emulsion-polymerization monomer-containing agitated-and-heated reactor contents an effective amount of an initiator for initiating the emulsion-polymerization reaction; maintaining the agitated-and-heated initiator-containing reactor contents at the reaction temperature; adding to the initiator-containing agitated-and-heated reactor contents the remainder of the emulsion-polymerizable monomer mixture; adding to the agitated-and-heated reactor contents, after the remainder of the emulsion-polymerizable monomer mixture has been added thereto but prior to completion of the emulsion-polymerization reaction, a polymeric resin, soluble or dispersible in water or in alkali, said resin having been produced either by a solution-polymerization method of by a bulk polymerization method, wherein the polymeric resin is produced from at least one ethylenically-unsaturated monomer selected from the group consisting of olefins, mono vinylidine aromatics, alpha beta ethylenically-unsaturated carboxylic acids and esters thereof, ethylenically-unsaturated dicarboxylic anhydrides, and mixtures thereof; and thereafter maintaining the reactor contents at the reaction temperature, with agitation, for a predetermined period of time.
 47. The method of claim 46 wherein the surfactant stabilizer is selected from the group consisting of a nonionic surfactant and an acrylic-based functional monomer.
 48. The method of claim 47 wherein the nonionic surfactant is an ethoxylated alkylphenol selected from the group consisting of nonylphenol and octylphenol, each said ethoxylated alkylphenol having at least 20 ethylene oxide units.
 49. The method of claim 47 wherein the acrylic-based functional monomer is selected from the group consisting of acrylic acid, methacrylic acid, polyethylene glycol monomethacrylate, and combinations thereof.
 50. The method of claim 47 wherein the acrylic-based functional monomer is methacrylic acid.
 51. The method of claim 46 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 1 to about 8 weight percent, based upon the weight of the reactor contents.
 52. The method of claim 46 wherein the surfactant stabilizer is present in the reactor contents in an amount of from about 2 to 4 weight percent, based upon the weight of the reactor contents.
 53. The method of claim 46 wherein the predetermined reaction temperature is about 60° to about 100° C., and wherein the inert atmosphere is nitrogen.
 54. The method of claim 46 wherein the ethylenically unsaturated monomers of the emulsion-polymerizable monomer mixture are selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, and combinations thereof.
 55. The method of claim 46 wherein the polymeric resin is present in an amount of about 2 to more than about 50 weight percent, based on the weight of the reactor contents.
 56. The method of claim 46 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of acrylic acid, methacrylic acid, styrene, alpha-methyl styrene, hydroxyethyl methacrylate, esters of acrylic acid and methacrylic acid, and mixtures thereof.
 57. The method of claim 46 wherein the ethylenically-unsaturated monomer utilized to make the polymeric resin is selected from the group consisting of styrene, alpha-methyl styrene, acrylic acid, and mixtures thereof.
 58. The method of claim 57 wherein the polymeric resin is a copolymer of styrene and acrylic acid and has a number-average molecular weight of about 1,000 to about 6,000.
 59. The method of claim 58 wherein the copolymer of the polymeric resin comprises three weight-parts styrene and one weight-part acrylic acid.
 60. The method of claim 59 wherein the number-average molecular weight of the copolymer is about 2,000 to about 4,000. 